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Lessons learnt from close encounters with severe windshear

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Lessons learnt from close encounters with severe windshear

Old 24th Aug 2017, 13:56
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Lessons learnt from close encounters with severe windshear

Jim Edds
✔ ‎@ExtremeStorms

This is nuts! KLM Amsterdam to Hong Kong landing just north of the eye of 100 mph+ Typhoon #Hato

12:33 PM - Aug 23, 2017.

Have just read the above extract from a media report of a KLM airliner landing at Hong Kong in the middle of a typhoon. The winds were horrendous and the windshear would not have been funny, either. The report was also on PPRuNe but then mysteriously disappeared.
............................................................ ............................................................ ............................................................ .........

Most of us would have encountered windshear during our flying career. Nowadays, Level D full flight simulators can be programmed for windshear training but rarely will you find this in general aviation desk top trainers. That is a pity because your first encounter with severe windshear can be frightening despite reading material that tells you what to do.

For example the Boeing 737 QRH offers this advice under the heading of Windshear Escape Maneuvre:
Disconnect autopilot. Press either TO/GA switch. Aggressively apply maximum thrust. Simultaneously roll wings level and rotated towards an initial pitch attitude of 15 degrees. Retract speed brakes. Follow flight director TO/GA guidance (if available). If TO/GA is not available, disconnect the autopilot and autothrottle and fly manually.
WARNING: Severe windshear may exceed the performance of the autopilot flight director system. The pilot flying must be prepared to disconnect the autopilot and fly manually.
Do not change flap or gear configuration until windshear is no longer a factor. Monitor vertical speed and altitude and do not attempt to regain lost airspeed until windshear is no longer a factor.
During my RAAF training on Tiger Moths and Wirraways in 1952, little was known about windshear and I do not recall our instructors talking about it. It was a case of learn on the job. Soon after graduation I flew Lincoln bombers at Townsville. The squadron also had a Mustang and a Wirraway.
On 15 November 1954, the local hospital at Townsville received an urgent request for a doctor to be flown to Hughenden to attend a severely burned man caught in a bush fire. The Hughenden hospital lacked the facilities to treat severe burn patients. A Dr G. Douglas quickly arrived at RAAF base Townsville where I was waiting to fly him to Hughenden in a Wirraway. The flight took an hour and a half and on arrival at Hughenden airport I was told to expect to wait for several hours before flying Dr Douglas back to Townsville.

There was no airport lighting at Hughenden so we had to be airborne before last light. I didn’t fancy flying at night over Tiger country between Hughenden and Townsville especially as the Wirraway had no radio aids to navigation apart from a single VHF set. Map reading at night would be impossible due to the remoteness of the region. All this was on my mind as the hours passed on the ground at Hughenden while impatiently awaiting the arrival of my passenger, Dr Douglas. In addition, the unexpected appearance of low black clouds on the horizon signified another problem.
Eventually a car arrived kicking up a dust trail and I bundled the doctor aboard after he had put on his parachute. In those days wearing of parachutes was mandatory. The weather was still clear along my intended take off and departure track but the sight of the black clouds rapidly approaching the airfield from behind my take off direction put some urgency into our departure. I saw the still limp windsock at the take off threshold just as heavy rain started at one end of the airfield. The take off roll seemed normal until half way down the runway when the airspeed stagnated. The departure end had tall trees beyond the runway and I was now concerned that I may not be able to clear them and it was too late to abort. I then saw another windsock to one side of the runway standing almost straight out signifying a serious tailwind.

I held the Wirraway on the ground for as long as I dared then gingerly pulled back on the stick. We scraped airborne and as the trees grew closer I decided to lower partial flap to clear them. It seemed a good idea at the time but I don’t know if I was just fooling myself.. We missed the tree tops by 50 feet, so maybe the flaps worked after all. Once clear I was able to retract flaps and accelerate to the normal climb speed of around 90 knots and set course for Townsville on the magnetic compass and directional gyro. Looking back over my shoulder I could see Hughenden airport disappearing in low black cloud and heavy rain. I didn’t know it at the time but that was windshear and it nearly got me into serious trouble. The rest of the trip was uneventful. The lesson I took with me was don’t take off or land when fast moving big black clouds are near the airport as the winds can become unpredictable.

Twenty years passed and this time I was flying a DCA Fokker Friendship during calibration of navigation aids at Charleville. Although I was pilot in command the co-pilot was another captain known for his belligerent personality. Two captains in the cockpit is often joked about as a lethal combination. I can now tell you there is a modicum of truth in that belief.

We were due to depart Charleville after completing the calibration testing when I became concerned about roll cloud weather rapidly approaching the airfield. I told the other captain I proposed to wait out the weather as I was concerned out the potential for windshear. My memory of the Wirraway episode was forever in my mind. The other captain was scornful of my decision and insisted we could get airborne well before the arrival of the approaching front. With some misgivings I allowed his forceful comments to sway my better judgement and we proceeded to taxi like the clappers to the runway to beat the front. There was an 8 knot tailwind judging by the windsock. Rain had reached the aerodrome boundary by then and urged by the other captain I started the take off run. Lift off speed in the F27 was around 90 knots if I recall, but during the take off roll which seemed abnormally long, the airspeed stopped accelerating. Fortunately the Charleville runway was quite long for a Friendship but even so we had barely reached VR by the end of the runway. Like the Wirraway at Hughenden 20 years earlier, I had made the mistake of bad airmanship by taking off when the signs of approaching windshear was plainly evident.

At least in the Wirraway I could plead ignorance of the dangers of windshear until I was forced to learn on the job so to speak. But I had no such excuse with the Charleville episode. It was simply weak captaincy allowing myself to be influenced by the forceful and aggressive personality of the co-pilot captain in the RH seat. A lesson today for those who teach Multi Crew Cooperation (MCC) courses as part of holding an ATPL.

There is a saying that good judgement comes from experience and a lot of that comes from bad judgement. The above stories are good examples of that.

And talking about windshear dangers, read the following link. Coincidently the aircraft involved was a Fokker F27 Friendship.

Centaurus is offline  
Old 26th Aug 2017, 04:42
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Join Date: Feb 2011
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Insurance Companies won't be impressed. Why would you even bother going near it, it's got sack me all over it.
PoppaJo is offline  
Old 26th Aug 2017, 11:57
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Why would you even bother going near it, it's got sack me all over it.
If you weren't there......
Capt Fathom is offline  
Old 27th Aug 2017, 05:25
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Fathom, they would have been well aware a few hours (even at the departure point) out of Honkers on what lies ahead.

I don't think many of us would have to be there to call this one out as nothing but pure negligence. KLM landing might have prompted other less than skill pilots in the area to also push on, however not everyone has the same ability to land in these conditions. Usually leads to an accident at some point.
wheels_down is offline  
Old 27th Aug 2017, 06:00
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"Simultaneously roll wings level and rotate towards an initial pitch attitude of 15 degrees" is standard terminology for Boeing.
The word "TOWARDS" is usually ignored. Attitude to at least maintain airspeed and ideally climb is what is required when flying manually.
It may be less than 15 degrees depending on thrust/weight/aircraft type and scenario.
TOGA with the windshear recovery program does a good job balancing the requirements i.e. follow FD commands when activated.
PW1830 is offline  

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